Use Session from HttpFoundation to store messages from Messenger.

[Pol Dellaiera]

I'm putting this code here as a reminder. Here's a quick working example of a Messenger using Session from HttpFoundation.
There's a thread on d.o. about it, I can't find it anymore, maybe @dawehner will help.

<?php

/**
 * @file
 * Contains \Drupal\service_container\Messenger.
 */

namespace Drupal\service_container\Messenger;

use Drupal\service_container\Legacy\Drupal7;
use Symfony\Component\HttpFoundation\Session\SessionInterface;

/**
 * Class that manage the messages in Drupal.
 */
class Messenger implements MessengerInterface {

  /**
   * The Drupal 7 legacy service.
   *
   * @var \Drupal\service_container\Legacy\Drupal7
   */
  protected $drupal7;

  /**
   * The Session service.
   *
   * @var \Symfony\Component\HttpFoundation\Session\Session;
   */
  protected $session;

  /**
   * Constructs a Messenger object.
   *
   * @param \Drupal\service_container\Legacy\Drupal7 $drupal7_service
   *    The Drupal 7 legacy service.
   * @param \Symfony\Component\HttpFoundation\Session\Session $session
   *    The Session service.
   */
  public function __construct(Drupal7 $drupal7_service, SessionInterface $session) {
    $this->drupal7 = $drupal7_service;
    $this->session = $session;
  }

  /**
   * {@inheritdoc}
   */
  public function addMessage($message, $type = self::STATUS, $repeat = FALSE) {
    $this->session->getFlashBag()->add($type, $message);
    return $this->session->getFlashBag()->peekAll();
  }

  /**
   * {@inheritdoc}
   */
  public function getMessages() {
    return $this->session->getFlashBag()->peekAll();
  }

  /**
   * {@inheritdoc}
   */
  public function getMessagesByType($type) {
    return $this->session->getFlashBag()->peek($type);
  }

  /**
   * {@inheritdoc}
   */
  public function deleteMessages() {
    $this->session->getFlashBag()->clear();
  }

  /**
   * {@inheritdoc}
   */
  public function deleteMessagesByType($type) {
    $this->session->getFlashBag()->get($type);
  }
}

There's nothing much left to do to get this working in D7. Ex: We could use a block to display the messages.

[Fabian Franz]

That is a won't-fix, we don't gain anything from mixing in the session component here.

[Fabian Franz]

As it is not integrated with the rest of Drupal.

The important thing is that we have the interface (that hopefully Drupal 8 will also use from 8.1.x on).

[Pol Dellaiera]

Yes I was looking for the thread about it. But anyway, this is just a code example on how to use it, as a reminder if we need it somewhere.